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E3S Web of Conferences 247, 01036 (2021) https://doi.org/10.1051/e3sconf/202124701036
ICEPP-2021
Cold mashing - Analysis and optimization of extraction
processes at low temperatures in the brewing process
Niklas Schöttke1,2, and Frank Rögener2,*
1Pfeifer & Langen GmbH & Co. KG, Aachener Straße 1042a, D-50858 Köln, Germany
2Technische Hochschule Köln, Institut für Anlagen und Verfahrenstechnik, Betzdorfer Str. 2, 50679 Köln, Germany
Abstract. According to indications, already 5,000 years ago beer was brewed without heating the mash,
i.e. in the cold mash process. Applying this old method, the question arises to what extent this traditional
knowledge can be integrated into today's brewing processes and to produce new beer styles at reduced
energy consumption. Since cold mashing is hardly explored, this work is dedicated to in-depth analysis
from a process and brewing point of view. Based on theoretical considerations of the mashing process, cold
mashing formulations were estimated and analysed. Parameters for the experimental investigations were
temperature, particle size of grinded grains, mixing ratio between malt and water, mashing time and the
application of various multistage extraction processes. Additionally, at the optimum cold mashing
conditions, a brew of about 10 L was produced, which confirmed the positive effects of the application of
cold mash: Fermentation time is significantly reduced due to the composition of the cold-extracted malt
components.
1 Introduction material transfer (the generated sugar is dissolved in
water). Mashing is the first biochemical process step of
The commercial beer market is currently dominated by brewing and completes the enzymatic degradation,
two production concepts, which to some extend compete which is initiated during malting. In this process,
with each other: large-scale industrial breweries, often enzymes are synthesized. These are essential for the
linked by corporate structures, are juxtaposed with small degradation of large molecules during the subsequent
privately run breweries. These so-called microbreweries mashing [10].
stand for craft beer and produce in small quantities According to Koljonen et al., the applied temperature
individual and - sometimes very unusual - beer styles profile during mashing determines the chemical
[1]. On the other hand, larger breweries often rely on composition of the malt wort [11].
beer styles, which appeal to the widest possible range of The balance between carbohydrates and proteins is
consumers [2]. Due to the highly competitive situation in important for beer brewing using barley malt, as high
the German beer market [3], the demand for new protein content reduces primarily the amount of
products ensures that brewers experiment with still available carbohydrates [10].
unknown or forgotten beer styles [1]. In accordance with Steiner et al. mention that proteins in the form of
current trends, possible health benefits of beer as a enzymes - also in combination with other substances
source of vitamins, minerals or antioxidants were such as polyphenols - affect the whole brewing process.
investigated [4-6]. Furthermore, energy and raw material Enzymes degrade starch, b-glucans, and proteins [10].
savings in the production process are a strong driving Temperature levels, as well as variations of the
force for all brewers to improve processes. However, the retention time, do not only affect the duration of mashing
Reinheitsgebot restricts openness to experiments in and the content of dissolved fermentable sugars, but also
German breweries. the degree of fermentation, flavour and foam of the beer
Against this background, archaeological discoveries [12].
associated with the production of the first beers are The quality of beer depends on several measurable
gaining in importance. There is evidence that 5,000 years parameters, which are based on the raw material and the
ago beers were produced without heating the mash, i.e. brewing conditions. These involve e.g. colour, clarity,
in the cold mash process [7, 8, 9]. However, if this foam appearance, and flavour [13]. But to a large extend,
brewing method has been used, very low alcohol the expression “quality” is defined by the individual
concentrations of not more than 2 vol.-% must be consumers [14, 15].
assumed [7]. This study was performed to evaluate the effect of
Mashing involves material conversion (water-soluble cold mashing and multiple staged mashing procedures
sugar is enzymatically produced out of starch) and on wort composition and the effect cold mashing would
*
Corresponding author: frank.roegener@th-koeln.de
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution
License 4.0 (http://creativecommons.org/licenses/by/4.0/).
E3S Web of Conferences 247, 01036 (2021) https://doi.org/10.1051/e3sconf/202124701036
ICEPP-2021
have on barley malt beer. Cold mashing is not common 2.5 Physical and chemical analyses
and is only used by a few experimental microbreweries
for the production of a few beer specialties. Malt and
2.5.1 Weighing
water are mixed without additional heating. Afterwards,
wort (extract) and brewers grain are separated from each For mass estimations, a precision scale type 3000 x 0.1g
other. Resting or warming of partial mashes is digital balance from Tykee was used. The accuracy is +/-
eliminated. After cold mashing and lautering, the 0.1 g.
resulting wort is boiled to kill germs like in the
conventional process [16].
From the results obtained, trends and correlations are 2.5.2 Temperature
derived, which are intended to explain on the one hand
For temperature estimations, a Pt1000 thermometer type
the reactions and on the other hand to design cold-mash GTH 175/PT from Giesinger was used. It has a
processes. Finally, economic conclusions are drawn from measurement range from -199.9 °C to +199.9 °C. The
the technical parameters obtained
accuracy is 0.1 °C.
.
2.5.3 Sugar content
2 Materials and methods
For the estimation of the Brix units, a refraktometer type
RHB-32SG from RZ was used. It has a measurement
2.1 Raw materials
range from 0 to 32. The accuracy is 0,2 %.
The investigations of cold mashing were carried out with
tap water supplied by Rheinenergie Köln, Germany. 2.5.4 pH
The malt employed for cold mashing was basic malt
of the type Viennese malt (manufacturer Weyermann), For the estimation of the pH an electode type SE 102 N
which is made of summer barley. The kiln drying from Knick was used. It has a measurement range from
process leads to a coloration of the malt between EBC pH 0-14 at an accuracy of +/- 0,01. The temperature
5.5 and EBC 6.5. The used malt consists of 66 wt.-% range is -5 – 100 °C.
carbohydrates, which contain 4 grams of sugar per 100
grams of malt.
2.5.5 Light microscopy
Two malt grists from Weyermann were used as
reference samples: Malt type 1 was Viennese malt (EBC: The analysis took place in the lab of WESTO Hydraulik
5,5 – 6,5), type 2 was Pilsen malt (EBC: 2,5 – 3,5). Both GmbH, Pulheim. A light microscope Typ: MM-KKE-M-
reference samples are offered as standard grain for C-U from Hydac was used, which allows enlargements
brewers without further specification. 2,5:1, 4:1, 10:1, and 20:1.
For the detection of complete sacharification of
starch, an iodine test with iodine N 50 solution was
employed. 2.5.6 HPLC
High pressure liquid chromatography (HPLC) is a
2.2 Milling chromatographic technique employed for the
identification and quantification of the individual organic
For milling, a cast iron malt mill with a capacity up to 30 components of a solution [10]. The estimation of the
kg/hour from Victoria was used. The grinding gap can be extract composition by HPLC took place at Pfeifer &
adjusted infinitely with the help of different washers. Langen Innovations Center in Elsdorf, Germany.
Accordingly, the denotations refer to employed washer
heigt, e.g. M 1,75 means a washer height of 1.75 mm.
2.5.7 Particle size
2.3 Mashing For the estimation of the particle size of the milled
grains, a sieving machine type Vibro from Retsch was
Mashing was done with a French press type Caffettiera used. The sieve tower was equipped in accordance with
French Press with a volume of 1 L from Bodum. The the current standard DIN 4188 (MEBAK).
height was 175 mm, the inner diameter was 90 mm.
Solid and liquid phase were separated by the filter
element of the French Press with a mesh size of 0.5 mm. 3 Results
Based on the theoretical background [16, 17], cold
2.4 Test brew based on cold mashing mashes were prepared and analyzed. For this purpose,
malt was used in various dry milled grain fractions.
A mashing kettle type DRE 3000 P W00 from Saier with Amongst others, milling conditions are supposed to have
a volume of 30 L was used for the production of cold a strong impact on wort quality [18]. Varied parameters
mashed beer. For the subsequent lautering a bottom plate in cold mashing were temperature, grain size of the malt,
type Läuterboden 357 mm from Mattmill was used. mixing ratio of malt and water, mash time and various
2
E3S Web of Conferences 247, 01036 (2021) https://doi.org/10.1051/e3sconf/202124701036
ICEPP-2021
multi-stage process variations. Investigated parameters 3.2 Influence of the malt load on the extract
were the concentration of dissolved extracts after concentration in cold mashing
mashing, the compositions of the extractives, the pH of
the mash and the qualitative detection of starch. The blue lines in Figure 2 mark all measurements in
Malt load was varied between 0.15 and 0.025 g Malt / which 9 grams of self-milled malt were used as an
gWater, as these values are typical of conventional extraction material. The green lines represent the use of
brewing processes [19]. 6 grams of malt, the red lines are based on a mixture of 3
Table 1 shows the performed investigations. grams of malt and 40 grams of water. 1.096
measurements were performed to estimate the curve of
Table 1. Investigations. the extract concentation as a function of malt type and
malt load (gmalt/gwater).
Investigated Analysis
Parameter Aim
material methods
Condition Optical
Malt grind Milling gap
of husks evaluation
Particle
size Sieving
distribu- machine
tion
Optical
Form
evaluation
factor
(partially light
estimation
microscopy)
Extract
Wort Refractometer /
mixing ratio concentra-
(extract) stop watch
tion
Fig. 2. Extract concentation as a function of malt type and malt
Extract
Tempera- Refractometer / load (gmalt/gwater) at room temperature.
concentra-
ture thermometer
tion At about 1.5-2 hours of mashing time, an optimum
Extract concerning the extract concentration can be seen. In
Residence composi- HPLC and pH
time tion and electrode
figure 3 a comparison between 2 and 6 hours of mashing
pH time is depicted.
Control of
Phases of Proof of starch
saccharif-
wort
ication
Influence
of cold Selected
Self brewed
mashing brewing
beer
on beer parameters
quality
3.1 Particle size analysis
The particle size of several self-milled grains as well as
two commercial grains was estimated. Type 1 stands for Fig. 3. Extract concentration after 2 and 6 hours mashing time
Viennese malt, type 2 stands for Pilsen malt, s. figure 1. at room temperature.
It can be seen, that when the mash time increases, the
influence of grain size on extract concentration
decreases.
M-1,75 was selected for further tests because M-1,5
and M-1,25 did not exhibit a sufficient lautering
behavior.
3.3 Influence of the temperature on the extract
concentration in cold mashing
During the test series described above, the temperature
Fig. 1. Particle size distribution of the self –milled malt grist was in a range between 17.5 and 19.5 °C. In the next
and the two commercial reference malt grists. stage of the study, it was examined to what extent
The analysis shows that the self-milled malt grists M- temperature fluctuations in the range between 11 and 26
1.5, M-1.75 and M-2 show particle size ranges °C show a result-relevant influence on the achieved
comparable to the commercial grist types 1 und 2. extract concentrations. Even if the temperature of the
mash was never below 17 °C or above 20 °C during the
3
E3S Web of Conferences 247, 01036 (2021) https://doi.org/10.1051/e3sconf/202124701036
ICEPP-2021
performance, the temperature range for the examination
was increased in order to evaluate to what extent the
temperatures in these areas influence the mashing
process. For the following trials, malt type M-1,75 was
used. A malt load of 0.15 gMalt/gWater - the mean value of
the investigated malt load - was kept constant and the
mashing temperature was varied. Figure 4 shows the
results.
Fig. 6. Influence of multistage processes on extract
concentrations.
As can be seen, the increase in the number of process
steps has a greater influence in the counterflow than in
the crossflow mode. A four-staged counterflow mashing
process is the preferred solution to achieve high extract
concentrations.
3.6 Test brew based on cold mashing
Fig. 4. Extract concentration as a function of cold mashing
temperature. The generated cold-mashed beer meets the criteria of a
light lager beer, s. table 2.
No clear relation between cold mash temperature and The taste turns out to be very light and the hops
extract concentration was detected. dominate the end of the sip.
Table 2. Characteristics of the generated cold-mashed beer.
3.4 Extract composition in single-stage cold
mashing Parameter Value
Extract concentration before rest 4.5 Brix
Selected mash samples with a malt load of 0.15 Extract concentration after rest 6.0 Brix
gMalt/gWater were examined chromatographically and the Extract concentration calculated 4.2 Brix
composition of the extract phase was determined. The Energy savings compared to
32.8%
composition of the worts studied is shown in Figure 5. conventional mashing
Relation of malt employed for cold
mashing compared to conventional 2.48
mashing
Original gravity 6.8 °Plato
Brewhouse effciency 28.8%
Final gravity 56.6%
Alcohol 2.4 wt.-%
4 Discussion
In the course of these studies, it was shown that small
temperature fluctuations have no direct influence on the
result of the cold mashing.
Fig. 5. Extract composition in single-stage cold mashing.
However, the selected particle size of the malt can be
The composition of the respective worts shows seen in the discord between mashing and lautering
increasing concentrations of maltose, glucose, and conditions. Accordingly, M-1,75 is chosen as the
dextrins with increasing mash time. preferred grain.
Due to the measured time histories, an ideal mash
time per mashing stage of 2 hours is determined. This
3.5 Extract composition in multistage cold mashing also in line with the lautering time on industrial scale.
For batchwise beer production, a matching of the two
In addition to the single-stage procedures, investigations
process step times is favourable.
of the extraction behavior were carried out also in multi-
The optimum mixing ratio of water and malt needs to
stage crossflow and counterflow. Based on the single-
be defined according to the specifications chosen
stage studies described before, malt M-1,75 was used.
individually. Considering the relatively smaller amount
As can be seen in figure 2, mash times larger than 2
of fermentable sugars in the generated wort and the
hours do not contribute to a significant increase of the
composition of the extract with a high proportion of
extract concentration. Accordingly, a mash time of two
short-chained carbohydrates, a reduced fermentation
hours per stage was chosen. Figure 6 shows the results of
the multistage investigations.
4
E3S Web of Conferences 247, 01036 (2021) https://doi.org/10.1051/e3sconf/202124701036
ICEPP-2021
time compared to conventional brewing processes is the required hop mass, which increases the cost-
expected. effectiveness of cold mashing. Furthermore, beers
Multi-stage processes involving four reaction stages produced by cold mash are in the trend of alcohol-
provide optimal results for a malt load of 0.175 g malt/g reduced beers and thus calorie-reduced foods. This fact
water in both cross current and the countercurrent mode. can be used as the basis for a successful marketing of the
By applying iodine tests, it was shown that the product.
extract dissolved in the wort does not contain any starch. The approaches shown in this work can be carried
However, the wort is clouded due to finely distributed out without costly technical conversion of existing
solid components. These are highly starchy, but they brewery equipment. Thus, cold mashing is an
could be saccharified by heating the wort. With regard to opportunity for each brewery to expand the product
the relationship between material conversion and transfer portfolio, create a new type of beer and enrich the beer
of substances during mashing, it could be shown that the market.
conversion of the substance is the decisive factor for
increasing the extract concentration.
In a final calculation of the energy and malt demand References
required for cold mashing, a comparison was drawn with 1. Deutscher Brauer-Bund e.V.: Zahl deutscher
conventional mashing. It turned out that cold mashing Brauereien wächst weiter. URL:
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E3S Web of Conferences 247, 01036 (2021) https://doi.org/10.1051/e3sconf/202124701036
ICEPP-2021
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